Functional effect of new atrial septal defect after percutaneous mitral valve repair using the MitraClip device

Percutaneous mitral valve repair using the MitraClip device has become a therapeutic alternative for high surgical risk patients with symptomatic mitral regurgitation. The procedure involves transseptal puncture and results in a new atrial septal defect (ASD) after withdrawal of the 22Fr guiding catheter. The functional effect of the new ASD is not defined. In 28 patients with symptomatic mitral regurgitation undergoing percutaneous mitral valve repair using the MitraClip device, 3-dimensional transesophageal echocardiography was used to measure by direct en face imaging the area of the new ASD. Analysis of the velocity-time integral (VTI) across the ASD after withdrawal of the guiding catheter allowed calculation of the shunt volume. Diastolic VTI of the mitral flow was determined before and after withdrawal of the guiding catheter to determine left ventricular inflow changes. Invasive left atrial pressure measurements were obtained during withdrawal of the guiding catheter. Regurgitant volume was reduced from 86±21 ml/beat before intervention to 43±22 ml/beat after intervention. The new ASD had an area of 0.19 cm2, 44% of the area of the 22Fr guiding catheter. Considering the VTI across the septal defect of 72±26 cm/s, the left-to-right atrial shunt volume was calculated to be 14±6 ml/beat. The diastolic forward flow across the mitral valve was reduced by 13±6 ml/beat immediately after withdrawal of the MitraClip guiding catheter. Mean left atrial pressure was reduced from 17±8 mm Hg with the guiding catheter still in the left atrium to 15±8 mm Hg after withdrawal of the guiding catheter. In conclusion, the creation of a new ASD as consequence of the large-diameter MitraClip guiding catheter results in volume and pressure relief of the left atrium. This contributes to the immediate hemodynamic changes implemented by the MitraClip procedure.